PHP: Hypertext Preprocessor (original) (raw)

Using remote files

As long as allow_url_fopen is enabled inphp.ini, you can use HTTP and FTP URLs with most of the functions that take a filename as a parameter. In addition, URLs can be used with the include,include_once, require andrequire_once statements (allow_url_include must be enabled for these). See Supported Protocols and Wrappers for more information about the protocols supported by PHP.

For example, you can use this to open a file on a remote web server, parse the output for the data you want, and then use that data in a database query, or simply to output it in a style matching the rest of your website.

Example #1 Getting the title of a remote page

<?php $file = fopen ("http://www.example.com/", "r"); if (!$file) { echo "Unable to open remote file.\n"; exit; } while (!feof ($file)) { <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>l</mi><mi>i</mi><mi>n</mi><mi>e</mi><mo>=</mo><mi>f</mi><mi>g</mi><mi>e</mi><mi>t</mi><mi>s</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">line = fgets (</annotation></semantics></math>line=fgets(file, 1024); /* This only works if the title and its tags are on one line */ if (preg_match ("@\<title\>(.*)\</title\>@i", <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>l</mi><mi>i</mi><mi>n</mi><mi>e</mi><mo separator="true">,</mo></mrow><annotation encoding="application/x-tex">line, </annotation></semantics></math>line,out)) { <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>t</mi><mi>i</mi><mi>t</mi><mi>l</mi><mi>e</mi><mo>=</mo></mrow><annotation encoding="application/x-tex">title = </annotation></semantics></math>title=out[1]; break; } } fclose($file); ?>

You can also write to files on an FTP server (provided that you have connected as a user with the correct access rights). You can only create new files using this method; if you try to overwrite a file that already exists, the fopen() call will fail.

To connect as a user other than 'anonymous', you need to specify the username (and possibly password) within the URL, such as 'ftp://user:password@ftp.example.com/path/to/file'. (You can use the same sort of syntax to access files viaHTTP when they require Basic authentication.)

Example #2 Storing data on a remote server

<?php $file = fopen ("ftp://ftp.example.com/incoming/outputfile", "w"); if (!$file) { echo "Unable to open remote file for writing.\n"; exit; } /* Write the data here. */ fwrite ($file, $_SERVER['HTTP_USER_AGENT'] . "\n"); fclose ($file); ?>

Note:

You might get the idea from the example above that you can use this technique to write to a remote log file. Unfortunately that would not work because the fopen() call will fail if the remote file already exists. To do distributed logging like that, you should take a look at syslog().

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